1. Field of the Invention
The present invention relates to an ion concentration setting apparatus for an ionic water generator which is capable of constantly generating alkaline ionic water and acidic ionic water having a desired concentration even from drink water such as city water, which has a different resistance in localities in accordance with kind and ratio of impurities mixed with water.
2. Description of the Prior Art
In a general ionic water generator, drink water such as city water is supplied to an electrolytic cell which is partitioned by an ion-exchange membrane and a DC voltage is applied between minus electrode and positive electrode disposed with the ion-exchange membrane therebetween. With the application of the voltage, alkaline ions such as calcium and sodium gather to the negative electrode side through the ion-exchange membrane, while acidic ions such as carbonic acid and chlorine gather to the positive electrode side through the ion-exchange membrane. Alkali ionic water, which has a swelling effect for softening things, a dissolving effect for dissolving things and a heat conducting effect for transferring heat quickly, is widely used because it advantageously enhances health of a human body and improves dyeing effect and sense of taste. Acidic ionic water, which has astringency for constricting things, a bleaching property for cleaning things and a disinfection, is used for beauty culture, cooking, sanitation, cleaning, etc.
The effect of such ionic water varies in accordance with the ion concentration. Therefore, in order to meet needs of a wide range of customers, it is important to adjust the concentration of the ionic water produced by selective switching thereof.
As well known, the concentration of ionic water is proportional to the value of the electrolytic current which flows in the electrolytic cell. For this reason, in a conventional ionic water generator, the voltage to be applied is sequentially set in advance, and the ion concentration is varied by varying the voltage to be applied.
Drink water supplied from city water has a quite different quality (particularly, the content of conductive substances represented by the resistivity) in localities because type and amount of impurities contained therein vary with districts. The electric resistivity of drink water therefore also varies with districts. Since the electric resistivity of drink water varies with districts, the electrolytic current (which flows from the positive pole to the negative pole through water in the electrolytic cell) caused by the application of a predetermined voltage to the electrolytic cell is different in accordance with the electric resistivity, thereby disadvantageously making the ion concentration of the ionic water produced at a predetermined voltage non-uniform. More specifically, in a conventional ionic water generator which controls the ion concentration by selectively switching the voltages to be applied to the electrolytic cell which are sequentially set in advance, the ion concentration varies with drink waters of respective districts, and it is actually impossible to obtain a constant ion concentration in any district by allying a constant voltage thereto.